In the Linux kernel, the following vulnerability has been resolved:
uprobes: Fix NULL pointer dereference in hprobe_expire()
Forking a task that has a pending uretprobe can oops the kernel with a NULL pointer dereference in the clone() path:
BUG: kernel NULL pointer dereference, address: 0000000000000018 Oops: 0002 [#1] SMP NOPTI RIP: 0010:hprobe_expire CR2: 0000000000000018 Call Trace: uprobe_copy_process copy_process kernel_clone __x64_sys_clone do_syscall_64 entry_SYSCALL_64_after_hwframe
This was found on real hosts on Meta fleet.
I've got the impression that this is what is happening:
CPU 1 CPU 2 (traced task) ----- ------------------- hit uprobe, prepare_uretprobe(): hprobe LEASED, refcount >= 1 uprobe_unregister() put_uprobe(): refcount -> 0 fork() -> dup_utask() hprobe_expire(hprobe, true) try_get_uprobe() -> NULL get_uprobe(NULL) <-- Oops
Only take the extra reference when the uprobe is non-NULL; a NULL means it is gone and is the correct value to return.
Covered by Rapid7
| Product | Vendor Advisory | Solution File | Added | Published |
|---|---|---|---|---|
| Amazon_linux_2023 | — | Upgrade kernel6.18-toolsUpgrade kernel6.18-debuginfo-common-x86_64Upgrade python3-perf6.18-debuginfoUpgrade kernel6.18-tools-debuginfoUpgrade kernel-livepatch-6.18.44-99.149Upgrade kernel6.18-develUpgrade bpftool6.18-debuginfoUpgrade kernel6.18-tools-develUpgrade microvm-kernel6.18Upgrade python3-perf6.18Upgrade kernel6.18-headersUpgrade kernel6.18-debuginfoUpgrade perf6.18Upgrade kernel6.18-modules-extraUpgrade perf6.18-debuginfoUpgrade kernel6.18-debuginfo-common-aarch64Upgrade kernel6.18Upgrade bpftool6.18Upgrade kernel6.18-modules-extra-common | Sep 30, 2026 | Aug 15, 2026 |
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